Not Applicable.
The present invention relates generally to lumbar support devices. More particularly, the present invention relates to lumbar support devices that are capable of changing shape, especially curvature in the lumbar region.
Lumbar support devices have been integrated into seats to change their shape, thereby allowing each occupant to adjust the support provided by the seat. The curvature of these devices is traditionally adjustable so that an occupant can operate the device to push the seat forward towards the occupant""s spinal column in the lumbar region. It is generally known to change the curvature of a lumbar support device using an actuator assembly that moves a support structure, such as a sinusoidal spring element. It is also well known to provide an actuator assembly that is either manually operated, using a handle or knob, or power assisted, using a drive motor and control switches. Increased curvature is usually accomplished by moving the support structure forward into the lumbar region, rotating sections of the support structure into the lumbar region, or bowing the support structure out into the lumbar region.
One aspect of the present invention relates to a strap lumbar device having a seat frame, a pair of brackets connected to the seat frame, a spring assembly connected to the pair of brackets in such a manner as to form a center section traversing the seat frame and a pair of cantilevered ends on opposite sides of the center section, and an actuator assembly operatively connecting the cantilevered ends. The pair of brackets respectively provide a pair of fulcrums about which the cantilevered ends can rotate.
In the preferred embodiment, the spring assembly has two integrally-formed, sinusoidal spring elements attached by a connector, and the center section of the spring assembly has a recessed portion. In other embodiments of the invention, a single sinusoidal spring has only one cantilevered end that rotates about a bracket, and a leaf spring is cantilevered about a pair of coil springs. The lumbar support device can be oriented horizontally or vertically in the seat frame, and the orientation of the cantilevered ends can be reversed.
In operation, the fulcrums allow the cantilevered ends to function as levers. The actuator assembly moves the levers which rotate about the fulcrums and bow the center section. The fulcrums are located between the distal end of the levers and the center section of the spring to stop the lever from sliding in the bracket and force the lever to rotate about the bracket.
Another aspect of the invention pertains to a lumbar support device comprising first and second mounts, a main body, and an actuator assembly. The mounts are spaced apart from each other and the main body has opposite end margins that are operatively connected to the mounts. The main body consists essentially of wire, and further comprises an intermediate portion that extends along the longitudinal trajectory of the main body between the first and second mounts. A point along the longitudinal trajectory defines first and second sub-portions of the intermediate portion and the wire is shaped and configured such that the first sub-portion has an average bending stiffness that is less than that of the second sub-portion. Additionally, the first end margin of the main body comprises a lever arm that extends in a cantilever manner and an actuator assembly is operatively connected to the main body via the lever arm. The actuator assembly is configured and adapted to induce a bending moment in the first end margin of the main body via the lever arm such that the longitudinal trajectory of the main body is selectively bendable between first and second positions. Due at least partially to the difference between the average bending stiffness of the first sub-portion and the average bending stiffness of the second sub-portion, the amount of curvature change of the longitudinal trajectory along the first sub-portion is greater than the curvature change of the longitudinal trajectory along the second sub-portion. In turn, this results in the curvature of the first sub-portion increases substantially more than that of the second sub-portion in response to the bending moment provided by the actuator assembly. Thus, the first sub-portion of the main body tends to bulge more than the second sub-portion when the longitudinal trajectory of the main body is selectively bent between first and second positions, thereby providing the main body with a desirable shape in an efficient manner. Furthermore, the fact that main body has such properties, and yet consists essentially of wire, allows the lumbar support device to be manufactured with low costs and simplifies the assembly of the lumbar support device.
In yet another aspect of the invention, a lumbar support device comprises first and second mounts, a main body, and an actuator assembly. The mounts are spaced apart from each other and the main body has opposite end margins that are operatively connected to the mounts. The first end margin comprises a lever arm that is formed by the wire that forms the main body. The lever arm extends in a cantilever manner and the actuator assembly is operatively connected to the main body via the lever arm in a manner such that the actuator assembly is capable of inducing an increasing bending moment to the first end margin. By forming the lever arm out of the wire that also forms the main body, the assembly procedure of the lumbar support device is simplified and the costs of the lumbar support device is substantially reduced.
In yet another aspect of the invention, a method of adjusting the contour of a seatback of a seat assembly is disclosed. The method comprises providing a seat assembly having a rigid seat frame and a seatback and operatively attaching first and second mounts to the seat frame in a manner such that the first and second mounts are spaced apart from each other adjacent the seatback. The method further comprises providing a main body that consists essentially of wire for supporting the seatback and for providing the seatback with a contour. The main body has first and second end margins and the wire is shaped and configured such that a first portion of the main body that extends along one of two contiguous halves of the longitudinal trajectory of the main body has a bending stiffness that is substantially less than a bending stiffness of a second portion of the main body that extends along the other of the two halves. The method yet further comprises operatively connecting the first end margin of the main body to the first mount and the second end margin to the second mount in a manner such that the main body supports the seatback and operatively connecting an actuator assembly to the main body. The actuator assembly is configured and adapted to selectively induce an increasing bending moment to at least one of the end margins of the main body such that the longitudinal trajectory of the main body increases in curvature in response to the increasing bending moment. The method yet further comprises adjusting the curvature of the main body from a first position to a second position via inducing an increasing bending moment to the at least one of the first and second end margins of the main body using the actuator assembly. The adjusting of the curvature of the main body causes the first portion of the main body to increase in curvature a greater amount than that of the second portion of the main body as a result of the bending stiffness of the first portion of the main body being substantially less than that of the second portion of the main body. This results in the contour of the seatback being adjusted in a desirable manner.
It is a purpose of the present invention to provide a lumbar support device that is simple and affordable to manufacture.
It is a further purpose of the present invention to provide a mechanically simplified lumbar support device that has a thin profile when flat.
Further advantages of the present invention will be apparent from the description below with reference to the accompanying drawings in which like numbers indicate like elements.